In general, a hydraulic excavator as a typical example of a construction machine has its vehicle body constituted by an automotive lower traveling structure and an upper revolving structure rotatably mounted on the lower traveling structure. A working mechanism performing an excavating work and the like is liftably provided on a front side of the upper revolving structure.
The upper revolving structure is largely constituted by a revolving frame forming a support structural body, a cab provided on a front side of the revolving frame and is on which an operator gets onboard, an engine mounted on a rear side of the revolving frame, a hydraulic pump mounted, on the engine, an exhaust gas post-treatment device connected to an exhaust side of the engine through an exhaust pipe, and a housing cover provided on the revolving frame covering these devices.
Here, an exhaust gas purifying device for removing harmful substances contained in the exhaust gas, a muffler device (exhaust muffler) for reducing a noise of the exhaust gas and the like are known as the exhaust gas post-treatment device. Moreover, a particulate matter removing device for removing particulate matters (PM), a NOx purifying device for purifying nitrogen oxides (NOx) and the like can be used singularly or in combination as appropriate, as the exhaust gas purifying device.
In recent years, in order to cope with exhaust gas control, a size of the exhaust gas post-treatment device tends to become larger. Thus, a constitution of mounting the heavy exhaust gas post-treatment device on a structure other than the engine or a structure such as the revolving frame and the like, for example, is adopted (see Patent Document 1).